Download Food, Nutrition and Health

Food,NutritionandHealth
‐VishalTrivedi
Food plays a very vital role in maintaining proper health and also helps to prevent and
cure many ailments. Eating can be defined as the consumption of food and liquid to sustain life
and to meet our body’s basic needs for growth, development, and function. The nutrients in food
enable the cells in our bodies to perform their necessary functions. A proper diet is essential from
the very early stages of life for proper growth, development and to remain active. Food
consumption, which largely depends on production and distribution, determines health and
nutrition of the population.
Nutrients that we obtain through food have vital effects on physical growth and
development, maintenance of normal body function, physical activity and health. Our diet must
provide all essential nutrients in the required amounts. Requirements of essential nutrients vary
with age, gender, physiological status and physical activity. Dietary intakes lower or higher than
the body requirements can lead to under-nutrition (deficiency diseases) or over-nutrition
(diseases of affluence) respectively. Eating too little food during the vulnerable periods of life
such as infancy, childhood, adolescence, pregnancy and lactation and eating too much at any age
can lead to harmful consequences. An adequate diet, providing all nutrients, is needed
throughout our lives. The nutrients must be obtained through a judicious choice and combination
of a variety of foodstuffs from different food groups. Carbohydrates, fats and proteins are
macronutrients, which are needed in large amounts. Vitamins and minerals constitute the
micronutrients and are required in small amounts. These nutrients are necessary for physiological
and biochemical processes by which the human body acquires, assimilates and utilizes food to
maintain health and activity (1).
Carbohydrates
Carbohydrates are either simple or complex, and are major sources of energy in all
human diets. Carbohydrate consumed in food yields 3.87 calories of energy per gram for simple
sugars, (2) and 3.57 to 4.12 calories per gram for complex carbohydrate in most other foods (3).
The carbohydrates are divided into four chemical groups: monosaccharides, disaccharides,
oligosaccharides, and polysaccharides. In general, the monosaccharides and disaccharides, which
are smaller (lower molecular weight) carbohydrates, are commonly referred to as sugars (4).
The simple carbohydrates, glucose and fructose, are found in fruits, vegetables and
honey, sucrose in sugar and lactose in milk, while the complex polysaccharides are starches in
cereals, millets, pulses and root vegetables and glycogen in animal foods. The other complex
carbohydrates which are resistant to digestion in the human digestive tract are cellulose in
vegetables and whole grains, and gums and pectins in vegetables, fruits and cereals, which
constitute the dietary fibre component. In India, 70-80% of total dietary calories are derived from
carbohydrates present in plant foods such as cereals, millets and pulses.
Dietary fibre delays and retards absorption of carbohydrates and fats and increases the
satiety value. Diets rich in fibre reduce glucose and lipids in blood and increase the bulk of the
stools. Diets rich in complex carbohydrates are healthier than low-fibre diets based on refined
and processed foods (5). Lactose from dairy products can be a major source of carbohydrate for
young children. In addition, milk represents an excellent source of high quality protein, calcium,
and riboflavin. In most populations, even those with low lactase activity, milk can be ingested in
small amounts, especially after meals with dilution by co-ingestion. Fermented dairy products
can be valuable items in the diet of most people irrespective of intestinal lactase status (6).
The Food and Agriculture Organization and World Health Organization jointly
recommend that national dietary guidelines set a goal of 55–75% of total energy from
carbohydrates, but only 10% directly from sugars (their term for simple carbohydrates) (7).
Proteins
Proteins are essential nutrients for the human body. Proteins are primary structural and
functional components of every living cell. Almost half the protein in our body is in the form of
muscle and the rest of it is in bone, cartilage and skin. Proteins are complex molecules composed
of different amino acids. Certain amino acids which are termed “essential”, have to be obtained
from proteins in the diet since they are not synthesized in the human body. Other nonessential
amino acids can be synthesized in the body to build proteins. Proteins perform a wide range of
functions and also provide energy (4 Kcal/g, 16.7 kJ/ g). Protein requirements vary with age,
physiological status and stress. More proteins are required by growing infants and children,
pregnant women and individuals during infections and illness or stress (8).
Animal foods like milk, meat, fish and eggs and plant foods such as pulses and legumes
are rich sources of proteins. Animal proteins are of high quality as they provide all the essential
amino acids in right proportions, while plant or vegetable proteins are not of the same quality
because of their low content of some of the essential amino acids. However, a combination of
cereals, millets and pulses provides most of the amino acids, which complement each other to
provide better quality proteins (1).
Meat, products from milk, eggs and fish are sources of complete protein (9). Vegetarian
sources of proteins include legumes, nuts, seeds and fruits. Legumes, some of which are
called pulses in certain parts of the world, have higher concentrations of amino acids and are
more complete sources of protein than whole grains and cereals. Protein powders – such
as casein, whey, egg, rice and soy are processed and manufactured sources of protein. These
protein powders may provide an additional source of protein for bodybuilders (10).
The generally accepted daily protein dietary allowance, measured as intake per kilogram
of body weight, is 0.8 g/kg (11).
Fat
Dietary fat consists of heterogeneous mixtures of triacylglycerols (triglycerides) and
small proportions of phospholipids, glycolipids, monoacylglycerols, diacylglycerols and
unsaponifiable fraction composed of fat soluble chemicals collectively designated as nonglyceride components. Fatty acids, the building blocks of various lipids, are classified into 3
groups: saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and polyunsaturated
fatty acids (PUFAs). Most of the SFAs consisting of straight even-numbered chains of 4-24
carbon atoms are classified as short (<10:0), medium (12:0 and 14:0) or long (16:0-24:0) chain
fatty acids. Unsaturated fatty acids (MUFAs and PUFAs) containing one or more double bonds
in trans configuration are called trans fatty acids (TFAs). PUFAs are grouped into two series (n-6
or n-3) depending on whether the double bond closest to the methyl end is located at C6 or C3
position. (12)
The small amount of fat present as integral component in each and every item of food
(invisible fat), the fat in processed and ready to eat foods (hidden fat) and visible fat (vegetable
oil, ghee, butter and vanasapti), used as cooking fat together contribute to total fat intake. (12)
Oils and fats such as butter, ghee and hydrogenated vegetable oil constitute dietary
visible fats. Fats are a concentrated source of energy providing 9 Kcal/g or 37.7kJ/g. Fats serve
as a vehicle for fat-soluble vitamins like vitamins A, D, E and K and carotenes and promote their
absorption. They are also sources of essential polyunsaturated fatty acids. It is necessary to have
adequate and good quality fat in the diet with sufficient polyunsaturated fatty acids in proper
proportions for meeting the requirements of essential fatty acids. The type and quantity of fat in
the daily diet influence the level of cholesterol and triglycerides in the blood. Diets should
include adequate amounts of fat particularly in the case of infants and children, to provide
concentrated energy since their energy needs per kg body weight are nearly twice those of adults.
Adults need to be cautioned to restrict intake of saturated fat and cholesterol. Excess of these
substances could lead to obesity, diabetes, cardiovascular disease and cancer. (1)
In general, adults should obtain at least 15% of their energy intake from dietary fats and
oils. Women of childbearing age should obtain at least 20% to better ensure an adequate intake
of essential fatty acids, needed for foetal and infant brain development. Active individuals who
are not obese may consume up to 35% fat energy, as long as saturated fatty acids do not exceed
10% of energy intake. Sedentary individuals should limit fat to not more than 30% of energy
intake and saturated fatty acids should be limited to less than 10% of intake (8).
Vitamin and mineral
Vitamins are chemical compounds required by the body in small amounts. An organic
chemical compound (or related set of compounds) is called a vitamin when the organism cannot
synthesize the compound in sufficient quantities, and must be obtained through the diet; thus, the
term "vitamin" is conditional upon the circumstances and the particular organism. For example,
ascorbic acid (vitamin C) is a vitamin for humans, but not for most other animal organisms (13).
Thirteen vitamins are universally recognized at present. Vitamins are classified by their
biological and chemical activity, not their structure.
Vitamins are essential for numerous body processes and for maintenance of the structure
of skin, bone, nerves, eye, brain, blood and mucous membrane. They are either water soluble or
fat-soluble. Vitamins A, D, E and K are fat-soluble, while vitamin C, and the B-complex
vitamins such as thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine
(B6), folic acid (B9) and cyanocobalamin (B12) are water soluble. Pro-vitamins like beta-carotene
are converted to vitamin A in the body. Fat soluble vitamins can be stored in the body while
water-soluble vitamins are not and get easily excreted in urine. Vitamins B-complex and C are
heat labile vitamins and are easily destroyed by heat, air or during drying, cooking and food
processing. (5) The details about the vitamins are given in the table below.
Minerals are inorganic elements found in body fluids and tissues. The important macro
minerals are sodium, potassium, calcium, phosphorus, magnesium and sulphur, while zinc,
copper, selenium, molybdenum, fluorine, cobalt, chromium and iodine are microminerals. They
are required for maintenance and integrity of skin, hair, nails, blood and soft tissues. They also
govern nerve cell transmission, acid/base and fluid balance, enzyme and hormone activity as
well as the blood- clotting processes (1).
Macrominerals
Many elements are essential in relative quantity; they are usually called "bulk minerals". Some
are structural, but many play a role as electrolytes. Elements with recommended dietary
allowance (RDA) greater than 200 mg/day are, in alphabetical order.

Calcium: a common electrolyte, but also needed structurally

Chlorine: as chloride ions; very common electrolyte

Magnesium: required for processing ATP and related reactions (builds bone, causes strong
peristalsis, increases flexibility, increases alkalinity)

Phosphorus: required component of bones; essential for energy processing

Potassium: a very common electrolyte (heart and nerve health)

Sodium: a very common electrolyte; in general not found in dietary supplements, despite
being needed in large quantities, because the ion is very common in food: typically
as sodium
chloride,
or
common
salt.
Excessive
sodium
consumption
can
deplete calcium and magnesium leading to high blood pressure and osteoporosis.

Sulfur: for three essential amino acids and therefore many proteins (skin, hair, nails, liver,
and pancreas). Sulfur is not consumed alone, but in the form of sulfur-containing amino
acids (17)
Trace minerals
Many elements are required in trace amounts, usually because they play a catalytic role
in enzymes. Some trace mineral elements (RDA < 200 mg/day) are, in alphabetical order:

Cobalt required for biosynthesis of vitamin B12 family of coenzymes. Animals cannot
biosynthesize B12, and must obtain this cobalt-containing vitamin in the diet

Copper required component of many redox enzymes, including cytochrome c oxidase

Chromium required for sugar metabolism

Iodine required not only for the biosynthesis of thyroxine but also it is presumed for other
important organs as breast, stomach, salivary glands, thymus, etc.

Iron required for many enzymes, and for hemoglobin and some other proteins

Manganese (processing of oxygen)

Molybdenum required for xanthine oxidase and related oxidases

Nickel present in urease


Selenium required for peroxidase (antioxidant proteins)
Zinc required for several enzymes such as carboxypeptidase, liver alcohol dehydrogenase,
and carbonic anhydrase (17)
World Health Organization Recommendations
The World Health Organization (WHO) has also published diet recommendations with
the goal of reducing risk of chronic disease. WHO recommendations are expressed as a range of
average daily intakes from lower to upper limits (14).
Total Energy
Sufficient to support normal growth, physical activity, and
body weigh t (body mass index = 20–22)
Total Fat
15%–30% of total energy
Saturated Fatty acids
0%–10% total energy
Polyunsaturated fatty acids
3%–7% total energy
Dietary cholesterol
0–300 mg/day
Total carbohydrate
55%–75% total energy
Complex carbohydrates
50%–75% total energy
Protein
10%–15% total energy
Salt
upper limit of 6 g/day (no lower limit set)
Dietary fiber
27–40 g/day
Refined sugars
0%–10% total energy
Table: Vitamins and its solubility, RDA, Deficiency diseases and common food sources (15, 16)
Deficiency Diseases
Food Sources
Fat
Recommend
ed Dietary
Allowances
(male, age
19-70)
900 µg
Night-blindness,
Hyperkeratosis, and
Keratomalacia
Liver, orange, ripe yellow fruits,
leafy vegetables, carrots,
pumpkin, squash, spinach, fish,
soy milk, milk
Vitamin B1
(Thiamine)
Vitamin B2
(Riboflavin)
Vitamin B3
(Niacin,
Niacinamide)
Vitamin B5
(Pantothenic acid)
Vitamin B6
(Pyridoxine,
pyridoxamine,
pyridoxal)
Vitamin B7
(Biotin)
Vitamin B9
(Folic acid, folinic
acid)
Vitamin B12
(Cyanocobalamin,
hydroxycobalamin,
methylcobalamin)
Vitamin C
(Ascorbic acid)
Vitamin D
(Cholecalciferol
(D3), Ergocalciferol
(D2))
Vitamin E
(Tocopherols,
tocotrienols)
Water
1.2 mg
Water
1.3 mg
Water
16.0 mg
Beriberi, WernickeKorsakoff syndrome
Ariboflavinosis, Glossitis,
Angular stomatitis
Pellagra
Pork, oatmeal, brown rice,
vegetables, potatoes, liver, eggs
Dairy products, bananas,
popcorn, green beans, asparagus
Meat, fish, eggs, many
vegetables, mushrooms, tree nuts
Water
5.0 mg
Paresthesia
Meat, broccoli, avocados
Water
1.3-1.7 mg
Anemia
Meat, vegetables, tree nuts,
bananas
Water
30 µg
Dermatitis, enteritis
Water
400 µg
Megaloblastic anemia
Raw egg yolk, liver, peanuts,
leafy green vegetables
Leafy vegetables, pasta, bread,
cereal, liver
Water
2.4 µg
Megaloblastic anemia
Meat and other animal products
Water
90 mg
Scurvy
Many fruits and vegetables, liver
Fat
10 µg
Rickets and Osteomalacia
Fish, eggs, liver, mushrooms
Fat
15 mg
Many fruits and vegetables, nuts
and seeds
Vitamin K
(phylloquinone,
menaquinones)
Fat
120 µg
Deficiency is very rare;
sterility in males and
abortions in females, mild
hemolytic anemia in
newborn infants
Bleeding diathesis
Vitamin Name
Solubil
ity
Vitamin A
(Ratinol, Retinal)
Leafy green vegetables such as
spinach, egg yolks, liver
References
1. Dietary Guidelines for Indian. (http://ninindia.org/DietaryguidelinesforIndiansFinaldraft.pdf)
2. USDA,
United
States
Department
of
Agriculture.
(http://ndb.nal.usda.gov/ndb/foods/show/6202)
3. FAO, Food energy: Methods of analysis and conversion factors. Agriculture and
Consumer Protection. (http://www.fao.org/docrep/006/y5022e/y5022e04.htm)
4. Flitsch SL, Ulijn RV (2003). Sugars tied to the spot. Nature 421 (6920): 219–20.
5. Sharma R (2005). Diet Management Guide. Daimond Pocket Books Ltd, pp 16-18.
6. FAO (1998). Carbohydrates in Human Nutrition: Report of a Joint FAO/WHO Expert
Consultation, Rome, 14-18 April 1997. Issue 66, p. 17.
7. Joint WHO/FAO expert consultation (2003). Geneva: World Health Organization. pp.
55–56.
8. Food
and
Nutritional
Security
of
Women
in
Agriculture.
(http://www.manage.gov.in/studymaterial/FNS-E.pdf)
9. Steinke FH, Waggle DH, Volgarev MN (1992). New protein foods in human health:
nutrition, prevention and therapy. CRC Press. pp. 91–100.
10. Lemon PW (1995). Do athletes need more dietary protein and amino acids? Int J Sport
Nutr (5): S39–61
11. Shane B, Mann N (2006). A Review of Issues of Dietary Protein Intake in Humans.
International Journal of Sport Nutrition and Exercise Metabolism (16): 129–152.
12. Nutrient Requirements and Recommended Dietary Allowances for Indians. A Report of
the Expert Group of the Indian Council of Medical Research, 2009. National Institute of
Nutritional, ICMR, Hydrabad. (http://icmr.nic.in/final/RDA-2010.pdf)
13. Fortmann, SP, Burda BU, Senger CA, Lin JS, Whitlock EP (2013). Vitamin and Mineral
Supplements in the Primary Prevention of Cardiovascular Disease and Cancer: An
Updated Systematic Evidence Review for the U.S. Preventive Services Task Force.
Annals of internal medicine 159 (12): 824–34.
14. Berdanier CD, Dwyer JT, Feldman EB (2007). Handbook of Nutrition and Food, Second
Edition, CRC Press, Boca Raton, FL, p. 347.
15. Dietary Reference Intakes: Vitamins. The National Academies 2011.
(http://www.iom.edu/Global/News%20Announcements/~/media/474B28C39EA34C43A
60A6D42CCE07427.ashx)
16. Kutsky, R.J. (1973). Handbook of Vitamins and Hormones. Van Nostrand Reinhold,
New York.
17. Nutrient. Wikipedia. (http://en.wikipedia.org/wiki/Nutrition)